Adaptive backplane system for electronic cards

ABSTRACT

An articulated backplane retainer system for electronic cards containing rigid and flexible domains. A rigid domain may be connected in some embodiments to an appended rigid domain carrying a connector for additional card. Brackets borne by the rigid domain may be used for ruggedizing the card-connector-rigid domain structure. Further ruggedization may be obtained by swivel connection between a rigid domain and an appended rigid domain. To further mechanically secure and limit the flexible backplane of the invention, a chain link member is provided for connecting flexibly pairs of rigid domains.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based upon U.S. Provisional PatentApplication No. 60/428,909, filed Nov. 26, 2002, entitled “ADAPTIVEBACKPLANCE SYSTEM FOR ELECTRONIC CARDS”, which is currently pending.

FIELD OF THE INVENTION

[0002] The present invention relates generally to electronic boardpackaging systems. More specifically the invention concerns a system fordebugging and integrating bus-based cards such as CompactPCI in which atransition card facility is supplemented. The invention also concerns anadaptive backplane system that can fit in space constrained locations.

BACKGROUND OF THE INVENTION

[0003] Printed circuit boards (PCBs) are used for interconnecting,mounting and packaging electronic components such as integratedcircuits. The boards (cards) can be arranged in card cages which providea constructional framework for sets of cards. This is illustratedschematically in FIG. 1, which is a configuration typical of CompactPCIstandard card cages and to which reference is now made. Backplane,(referred to also as motherboard) 10 is disposed within card cage 12.Backplane 10, bears eight connectors 14, unto which boards can beplugged.

[0004] A plug-in card is connected to the backplane as describedschematically in FIG. 2A to which reference is now made. Male connector16 harbors the female connector 18 onto which the board 20 is affixed.In the CompactPCI connectors, as described in FIG. 2B. Male connector 22contains pins 24 which accomplish the electric connection between thecard (not shown) and the backplane to which it is plugged.

[0005] Owing to the compact configuration standards of the backplanesystem such as in the VME and in the CompactPCI (cPCI), the access toany location on the plugged-in board, except for peripheral sites, isdifficult. Probes of test equipment have to be physically connected tospecific terminals on the plugged-in boards, typically disposed in cardcages. For developers of hardware systems the accessibility tocomponents and test points on the cards is an exceptionally importantissue, primarily for debugging of the circuits and their integrationwith the software. Three strategies for enhancing the accessibility intosuch cards are presently employed:

[0006] 1. Leaving vacant connectors in standard card cages. Such anundertaking leaves more room for probes to be connected to the cards'components and test points. The extra accessibility is gained however atthe cost of empty connector, which downgrades system integrationcapabilities.

[0007] 2. Installing dedicated debugging ports and test points on thecards, which are relatively easily accessible through the front panel,even when installed in card cages.

[0008] 3. Using card cages dedicated for ease of accessibility.

[0009] A previously employed strategy, namely the extender cardarrangement, is no longer popular among developers. This disinclinationstems from the significant influence that such an arrangement has onsignal integrity, and from the limitation on bug reconstruction thatsuch an arrangement confers.

[0010] Some backplane systems use a supplementary set of card slot inthe rear side of the backplane as is schematically shown in FIG. 3 towhich reference is now made. On both surfaces of backplane card arearranged male connectors.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a schematic prior art description of a backplane carddisposed within a card cage;

[0012]FIG. 2A is a schematic isometric description of a plugged-in cardin a prior art connector of a backplane card;

[0013]FIG. 2B is a schematic description of a connector of a backplaneshowing the arrangement of pins in a connector of a backplane of theprior art;

[0014]FIG. 3 is a schematic description of a backplane system of theprior art containing two set of connectors on both sides of thebackplane;

[0015]FIG. 4 is a schematic isometric view showing a bent flexible cardof the invention;

[0016]FIG. 5 is a schematic description of a portion of a backplane cardof the invention with supplementary cards;

[0017]FIG. 6 is a schematic enlarged view of a backplane system of theinvention showing an appended rigid domain and plugged in cards;

[0018]FIG. 7A is a schematic description of a rigid domain pair ofbackplane system of the invention;

[0019]FIG. 7B is a schematic enlarged view of the connection between therigid domains of a rigid domain pair of the invention;

[0020]FIG. 8 is a schematic view of a ruggedized section of an ABP ofthe invention, showing brackets;

[0021]FIG. 9 is a schematic view of a section of an ABP showing tworigid domain pairs showing the folded layers connecting the appendedrigid domains with the backplane rigid domains;

[0022]FIG. 10A is a schematic description of a swivel connection betweenbackplane rigid domain and an appended matching rigid domain;

[0023]FIG. 10B is a schematic description of a swivel connection betweenbackplane rigid domain and an appended matching rigid domain, with thepivot drawn out;

[0024]FIG. 11A is a schematic description of a link connector alignedwith a swivel connection and the pivot thereof drawn out on its axis;

[0025]FIG. 11B is a schematic description of a link connector in a nearattached position;

[0026]FIG. 12A is a schematic side view description of a backplanesystem of the invention, wherein link members are interconnected;

[0027]FIG. 12B is a schematic side view description of a backplanesystem of the invention, wherein link members are interconnected andsome rigid domains have moved with respect to their positions asdescribed in FIG. 12A;

[0028]FIG. 13 is a schematic description of the applicable electricalconnection schemes between matching rigid domains in accordance with thepresent invention;

[0029]FIG. 14 is a general description of a backplane system of theinvention including cards and supplementary card, showing ejectors andlegs.

SUMMARY OF THE INVENTION

[0030] The present invention provides an articulated electronic cardretainer system that can be implemented in a bus-based card-cagedsystems such as VME or CompactPCI electronic card standards. Themechanical flexibility of the system allows relative easy access tocomponents and test points on the plug-in cards.

[0031] In one embodiment of the present invention, a bracketed plug-incard provides a mechanical strengthening benefit. The bracket stabilizesmechanically the connection between the plug-in card and the backplane,a connection which is subjected to excessive mechanical strains in theflexible backplane.

[0032] In accordance with one aspect of the present invention, amechanically enhanced, flexible backplane in the form of an articulatedPCB (printed circuit board)is provided. Typically a backplane system ofthe invention implements a set of transition cards, connected to the PCBby a matching set of connectors carried by rigid domains. To furthermechanically secure the flexible backplane of the invention, a chainlink member is provided, for connecting mechanically rigid domain pairsand facilitate a secure yet relatively free relative movement of the twomembers of the pair.

DETAILED DESRIPTION OF THE PRESENT INVENTION

[0033] In accordance with the present invention, an articulatedbackplane (ABP) is provided, in which rigid domains bearing the malebackplane connectors, alternate with flexible inter-connector domains(FD). This conformation is better explained in reference to FIG. 4 whichillustrates schematically a ABP generally designated 30 in accordancewith an embodiment of the invention. Rigid members (RM) 32 of the PCBbear each a male connector 34 which is capable of harboring a compatibleelectronic card such as cards 36. Besides the rigid domains, the card ofthe invention includes at least one flexible domain 38. Male connector34 harbors a female connector 40 onto which the card 36 is affixed. Thegeometrical dimensions and electrical properties of the connectors andthe space between them are defined by the appropriate standard, such asVME, or CompactPCI and must not impair signal integrity.

[0034] The FDs are flexible due to their reduced thickness and theirconstitution. For example, the RMs of the invention are made, typically,like common PCBs, of 6-32 layers of rigid fiberglass typicallyimpregnated with epoxy or polyimide. The FD is made of 2-32 layers offlexible plastic resin, typically Kapton® polyimide with no fiberglassreinforcement.

[0035] VME and cPCI Backplane Card Architecture

[0036] The present invention provides an electronic card retainer thatcan be implemented in any bus-based card-caged systems such as the aboveelectronic card standards. The mechanical flexibility of the systemallows the developer to gain relative easy access to components and testpoints on the plug-in cards. For this reason, the system of the presentinvention is particularly beneficial for those developers whooccasionally or frequently have a need for probing the components andtest points on the cards in the course of development and integration ofbus-based, card-caged systems.

[0037] In one embodiment of the present invention, a bracketed plug-incard was described which provided a mechanical strengthening benefit.The bracket stabilizes mechanically the connection between the plug-incard and the backplane, a connection which is subjected to excessivemechanical strains in the flexible backplane.

[0038] In accordance with one aspect of the present invention, amechanically enhanced, flexible backplane (ABP) in the form of anarticulated PCB (printed circuit board) is provided. Typically abackplane system of the invention implements a set of transition cards,connected to the PCB by a matching set of connectors. The architecturalfeatures of this aspect of the invention are better explained withreference to FIG. 5. The ABP 44, of which only a portion is shown,includes rigid domains (RDs) such as RD 46, onto which connectors, suchas connector 48 are affixed. A plug-in card 50 is inserted into therespective RD, through mating connector 52 to which the plug-in card 50is attached. In the other side of the ABP, a transition card (TC) 54 isinserted into the respective RD through connector 56. The configurationof the ABP of the invention at the level of the RDs is better explainedwith reference to FIG. 6, which is an enlarged schematic view of theconnection between plug-in cards and the RDs. Connector 58, is pluggedin connector 60 which is affixed to a backplane rigid domain (BPRD) 62.An appended rigid domain (ARD) 64 bears a connector 66 into which amatching card connector 68 is plugged.

[0039] The Electric Connections between the BPRD and the Matching ARD

[0040] As can be seen in FIG. 6, each BPRD contains a set of continuouslayers 70 running through the BPRDs of the ABP. In accordance with apreferred embodiment of the invention, the BPRD contain two sets offlexible layers. The connection between the ARDs of the ABP ismaintained by the circuits associated with the layers out of which theABP is made. Some of the layers contain the circuits which maintain theelectric connections between the ARDs and connection to the ports andother connections on the ARD on the ABP.

[0041] In FIG. 7A to which reference is now made, the layers 72 arefolded in a different folding scheme. This folding scheme allows moreflexibility of the supplementary card positioning relative to the BPRDand associated card. In FIG. 7B an enlarged view of the folding schemeshows how the flexible layers are folded connecting opposite sides ofthe front and rear ARDs. The relationship between BPRD 76 and the ARD78, Which constitute a rigid domain pair is such that their relativemovement is more slack than in the tighter folding schemes.

[0042] Plug-in Board Brackets and Ruggedization

[0043] In FIG. 8 to which reference is now made, a BPRD 82 into which aplug-in card 84 is installed is fitted with a bracket 86. The ARD 88 isalso fitted with bracket 90, which corresponds in length with the heightof plug-in card 92. The adjacent RD pair 94 is shown without plug-incards and brackets. In FIG. 9 to which reference is now made, twoadjacent RD pairs of a ABP are shown. Bracket 98 is applied to BPRD 100and another bracket 102 is applied to the respective ARD 104. Anadjacent RD pair 106 is connected by a flexible domain to BPRD 100.

[0044] Mutually Securing the BPRD and the Matching ARD

[0045] To enhance the ruggedness of the backplane system of theinvention, yet keep it flexible for convenient access into theplugged-in boards, further measures are taken. In FIG. 10A to whichreference is now made, another aspect of the invention is describedschematically in which a swivel connecting between a BPRD and thematching ARD is provided. Accordingly, to ARD 110, associated withbracket 112, are attached swivel members 114. Swivel members 114 areeach pivotally fitted to the matching swivel members 116, which areattached to BPRD 118. Bracket 120 is associated with BPRD 118. In FIG.10B the same construction is shown, with the pivot 122 drawn out alongits axis out of the pivot's bore 124. Pivot 122 locks the two members ofthe RD pair together allowing rotational movement around the pivot.

[0046] Stretch and Twist Limiter Chain

[0047] To further mechanically secure the flexible backplane of theinvention, a chain link member is provided. From the interlinkedplurality of which links a mechanically securing chain is made. Thechain thus applied provides a limit to the twist and stretch that can beimposed on the backplane of the invention. To describe the limiterchain, reference is now made to FIG. 11A. Link member 170 contains fourholes, of which 172 is used for driving a fastening means such as arivet to pivot 122, shown drawn out on its axis 123. The two lateralholes 174 and 176 are used for pivotally connecting the link member 170to adjacent link members (not shown). In FIG. 11B the link member 170 isshown in a near fastened position, whereby the link member 170 isapproached to the RD pair for locking. Hole 178 is used for fasteninglink member 170 to the pivot (not shown). FIG. 12A is a schematic sideview of a portion of a backplane of the invention, with the link memberssuch as link 180 installed. The link member 180, is disposed between thepair members BPRD 182 and ARD 184. Link 180 is connected pivotally tolink member 186 at hole 188, such that a relative rotational movementbetween the link members can be achieved. Each member of the RD pair,for example ARD 180 and BPRD 182 cane perform relative rotationalmovement around the axis 190. In a preferred embodiment of theinvention, the link members such as link member 180, are fixed to onebracket of the RD pair. This is fixation is typically performed byaffixing element such as a rivet or a screw 192.

[0048] The relative movement of the two members of the RD pair isfurther described in FIG. 12B to which reference is now made. BPRD 194and ARD 196 constitute a rigid domain pair (RD pair). BPRD 194 has movedin the direction of arrow 198 around pivot 200, whereas ARD 196 hasremained static with respect to the pivot 200. ARD 202 turns aroundpivot 204 together with link member 206, to which it is attached.

[0049] In FIG. 13 a schematic description of the applicable connectingschemes between matching rigid domains. ARD 220 and BPRD 222 constitutea rigid domain pair. The electrical connection between the two membersof the pair is maintained through a right side flexible connection 224.ARD 228 and BPRD 230 constitute another rigid domain pair, in this pairthe electric connection is maintained through a left side flexibleconnection 232. In another rigid domain pair, ARD 234 and BPRD 236 areinterconnected by a folded flexible connection 238. In FIG. 14 to whichreference is now made, a complete system of a backplane and includedfront or main cards such as card 250, and rear supplementary cards suchas card 252. Legs 254 support the backplane system, providing stabilitywhich is required in the course of handling and probing the backplanesystem. Ejectors such as ejectors 256 are required for retrieving theplugged cards. The cards which are forcibly pushed into the multi-pinconnector are ejected usually by applying a force provided by theleveraging of the ejectors. In accordance with the present invention,each injector is pivoted on a bracket pivot thereby facilitatingforceful retrieval of the card.

[0050] The mechanical flexibility of the backplane system of theinvention is nevertheless an advantage that can be used for applicationsin which space is a very limited such that bending or convoluting abackplane system may become useful. Such extreme requirements for spaceare typical of vehicles, especially of aerospace carriers, as well as inships and submarines and ships. To fully express the utility of theflexible backplane as a flexible structure for either handling or forpermanent deployment, a flexible card cage is advantageously used. Theflexible card cage, which may be articulated, can be bent or convoluted,yet provide the backplane system an external protection.

1. An articulated backplane electronic card retainer, comprising: atleast two rigid domains traversing the backplane, and flexible domainsflanking at least both sides of said rigid domain.
 2. An articulatedbackplane electronic card retainer as in claim 1 further comprising atleast one card bracket connected to at least one rigid domain forruggedizing said card retainer.
 3. A mechanically strengthenedarticulated flexible backplane system, comprising: at least one bracketfor at least a plugged-in board, wherein said bracket is connected to arigid domain of said backplane; and a pivot locking together pivotallymembers of a rigid domain pair.
 4. A mechanically strengthenedarticulated flexible backplane system as in claim 3 further including anappended rigid domain per at least one rigid domain, forming a rigiddomain pair.
 5. A mechanically strengthened articulated flexiblebackplane system as in claim 3 and wherein said system is ruggedizedfurther by having a link member interconnecting two adjacent members ofsaid at least one rigid domain pair.
 6. A method for ruggedizing anarticulated electrical backplane system whereby each rigid domainfurther includes an appended rigid domain unto which supplementary cardscan be plugged in, and wherein at least one of said rigid domains isfitted with brackets, and wherein each rigid domain having an appendedrigid domain is interconnected with said appended rigid domain.
 7. Amethod for ruggedizing an articulated electrical backplane as in claim 6whereby each rigid domain further including an appended rigid domainunto which supplementary cards can be plugged in, and wherein each rigiddomain having an appended rigid domain is interconnected with anotherrigid domain having a respective appended rigid domain.